In recent years, designs for large vehicles have advanced and become more sophisticated and complex. Land vehicles such as recreational vehicles (RVs) and busses have grown in size, complexity, and the number of features that they offer. Likewise, water vehicles, such as yachts and other boating vehicles, have also evolved to provide larger living spaces, more technology, and improved heating, air conditioning, refrigeration, lighting, and entertainment options for users.
While these features improve the comfort and functionality of the vehicles for users, they also come at a cost, specifically with respect to power consumption. Traditionally, recreational vehicles have strived to provide users with the same luxuries as a stationary home, but most auxiliary power solutions suffer from numerous limitations. For example, the power systems for these type of vehicles have used external engine powered generators, apart from the main drive engine, to supply the electrical energy require to operate the devices needed by the operator. The generator engines range in size of 2 kilowatts to 50+ kilowatts and they consume considerable space, add large amounts of weight to the vehicles and create considerable amounts of emissions. Further complicating the addition of generators, EPA Generation IV diesel rules are currently being applied to use of generators, which further drives up the cost, complexity, and size of generators and increases reliability issues. Relying on the main engine as a primary source of power, however, is not an effective solution due to its inefficiency in powering the nominal loads and the common use of 12V as the primary operating voltage of engine systems. In other systems, batteries have been used as a secondary power source. However, the weight, size, and life expectancy of traditional batteries prevent them from being the core auxiliary power components for vehicles.
For many years, the standard operating voltage for most vehicles has been 12 volts DC, which is also the default or standard for most platforms globally. Batteries, computers, starter motor, lighting, and all of loads have been developed for mobile platforms. The limitation of 12 volts DC, however, is based in physics defined as Ohm's law and electrical work.Ohms law: V=I*R Where V=volts, I=Amps, and R=Resistance. Electrical work is defined as:W=V*A Where W=Watts, V=Volts, and A=Amps.
To power a device of any type it requires work to be done, in this case electrical work or watts. For large tasks more work is required. For example assume a vessel requires 8,000 watts to operate all of its systems. If you were to provide that power using 12 volts the amperage (or current) required to deliver that amount of work would 667 amps which is an extremely large number and is not practical due to electrical losses and safety.
One solution to deal with the high current levels is to increase the voltage. By increasing the voltage, the same amount of power could be provided at a much lower amperage. However, higher voltages bring additional regulations and requirements. Any voltage above 60 volts DC is classified as a high voltage application by the Federal Energy Regulatory Commission (FERC) and the North American Electric Reliability Corporation (NERC). When working with voltages above 60 volts DC there are multiple regulations and safety consideration that add cost and complexity. These additional restrictions increase liability and require specially trained personal to maintain such systems. In most applications the mobile transportation systems described above are maintained by the owners or work crew that operate the vehicle for the tasks it was designed for and not necessary trained for high voltage work. Therefore it is advantage to the owners and operators of the vehicles to have electrical systems that are safe for them to maintain at lower voltages.
These larger power high voltage systems are often integrated into the original vehicle platform. When integrated into the vehicle architecture the computer system, controls, software, and mechanical items are rigidly integrated limiting the options that can be done to the vehicle by the Recreation Vehicle Manufacturer or the Commercial Vehicle manufacturer. The commercial and recreation vehicle manufacturers' traditionally design their vehicles around a mass produced platform either an engine or a complete drivetrain from a larger volume equipment manufacturer. They then construct the specialized vehicle components and accessories around the base platform. Due to the complexity and liability of the high voltage integrated solutions the up fitting manufacturer cannot utilize or adapt these integrated system into their platforms without significant research and expense.
Another approach for powering auxiliary systems has been to use AC (alternating Current) generators which operate at the same voltages and wave forms as most home systems. In North America the standard is 120V at 60 Hertz. Using a generator allows the manufacturer and operators to use commonly available appliances that run on 120 V AC and tools which reduces complexity and cost. The limitations on these types of generators is the regulation quality of the wave form. As shown in FIG. 1A, the power delivered to our homes are well regulated 60 hertz cycles. Generators, however, do not have the same capabilities as large power facilities are susceptible to variation which causes incomplete and often damaging wave forms to appliances and electronics, as shown in FIG. 1B.
While many small volume manufacturers desire to develop auxiliary power systems and add on hybridization systems that are uniquely customized to their vehicle or system, the cost and complexity of developing such systems makes them unattainable. A cost competitive, scalable, and customizable third party hybrid solution that easily integrates with existing power solutions would solve this need.
Accordingly, an improved secondary power system that is scalable, customizable, and integratable with existing power solutions is needed in the industry.